COLLAPSIBLE WHEELCHAIR

Abstract: The invention relates to a collapsible wheelchair comprising a frame comprising: a first side frame; a second side frame substantially the same as the first side frame; coupling means holding the two said side frames at least in the operative situation in the same positions at a mutual distance. The invention provides a wheelchair which has the feature that each side frame comprises: a first middle sub-frame, a front sub-frame, a rear sub-frame; the front and rear sub-frames are pivotable relative to the first middle sub-frame by means of a hinge joint; the coupling means are embodied as spacers holding corresponding sub-frames at fixed mutual distance; a second middle sub-frame is arranged between the front and rear sub-frame for pivoting relative to both these sub-frames by means of a hinge joint such that each side frame, and therefore the whole frame, can be folded round horizontal pivot axes until the three sub-frames lie at least substantially on top of each other; and stop means are present between a middle sub-frame and at least one of the other sub-frames which determine a stable operating position of the wheelchair.

Description: COLLAPSIBLE WHEELCHAIR The invention relates to a collapsable wheelchair comprising: a frame comprising: a first side frame; a second side frame substantially the same as the first side frame; coupling means holding the two said side frames at least in the operative situation in the same positions at a mutual distance; wheels arranged on the frame; a seat arranged on the frame; and a seat back arranged on the frame. Such a wheelchair is known. In the known wheelchair the side frames are movable toward each other by means of a hinged cross connection by exerting an inward pressure force from the sides. In the thus obtained folded situation the wheelchair has the same dimensions in the vertical plane as in the non-collapsed state. The invention has for its object to embody a wheelchair such that in collapsed state it occupies considerably less effective space than the known wheelchair and for instance has dimensions such that it can be taken as hand-luggage aboard an aircraft which for obvious reasons is considerably more practical for a wheelchair user. The wheelchair user can transport himself or, if necessary, be transported with the help of a third party into the aircraft. The wheelchair can there be folded up to dimensions which are at most equal to the maximum permissible dimensions for hand-luggage. After the flight the wheelchair is again immediately available to the wheelchair user. Also in the case of other forms of transport such as public transport or a car it may be desired that a wheelchair can be collapsed to comparatively small dimensions . With a view to the above the invention provides a collapsable wheelchair which has the feature that each side frame comprises: a first middle sub-frame which in the operative situation extends more or less horizontally, at least roughly at the height of the seat; a front sub-frame which in the operative situation extends from the front side of the first middle sub-frame inclining downward in forward direction and which bears a relatively small front wheel; a rear sub-frame which in the operative situation extends from the rear side of the first middle sub-frame inclining upward in rearward direction and which bears a relatively large rear wheel and together with the other rear sub-frame supports the seat back; the front and rear sub-frames are pivotable relative to the first middle sub-frame by means of a hinge joint; the coupling means are embodied as spacers holding corresponding sub-frames at fixed mutual distance; a second middle sub-frame is arranged between the front and rear sub-frame for pivoting relative to both these sub- frames by means of a hinge joint such that each side frame, and thus the whole frame, can be folded round horizontal pivot axes until the three sub-frames lie at least substantially on top of each other; and stop means are present between a middle sub-frame and at least one of the other sub-frames which determine a stable operating position of the wheelchair. It is advantageous to be able to adjust the diverse mutual relationships, in particular the angular positions of the component parts, in accordance with the wishes of the user. For this purpose the wheelchair can have the feature that the location of the hinge joint between the first middle sub-frame and the rear sub-frame is adjustable along that rear sub-frame. The wheelchair can also have the feature that the location of the hinge joint between the second middle sub- frame and the front sub-frame is adjustable along that front sub-frame. The wheelchair can have the additional feature that the length of the second middle sub-frame is adjustable. Other than in the case of the known wheelchair briefly described above, wherein a pivotable scissor construction mutually couples the two side frames, in the wheelchair according to the invention the side frames must be as inherently stiff as possible in the vertical plane. To this end the wheelchair according to the invention can display the feature that, in the main plane of the side frame and at least in the zone adjoining the hinge joint to the front sub- frame, the first middle sub-frame has larger dimensions than in transverse direction for increasing the bending stiffness in that plane. The first middle sub-frame can for instance be more or less plate-like, and have an increasing vertical dimension at least in the direction of its forward side. However, in order to save as much weight as possible use can also be made of a cut-away structure. The requirement of an increased bending stiffness also applies for the front sub-frame, but to a somewhat lesser extent. In this respect the wheelchair can have the feature that in the main plane of the side frame and at least in the zone adjoining the hinge joint to the first middle sub-frame, the front sub-frame has a larger dimension than in transverse direction for increasing the bending stiffness in that plane. In order to enable the easiest possible folding of the wheelchair after detaching the wheels it can display the special feature that the rear wheels are releasably coupled to the rear sub-frame by means of a rapid-action coupling. This variant can have the particular characteristic that the rear sub-frame bears a releasable block which supports a shaft to which a rear wheel is releasably coupled, which block supports the shaft at an angle determining the alignment angle of the rear wheel. The longitudinal position of the rear wheels is to a large extent decisive for the balance of the wheelchair. As this balance differs from user to user and may also depend on the adjustment of the diverse, mutually adjustable parts and the parts of adjustable length, the wheelchair can display the special feature that the position of the shaft is adjustable in the travel direction of the rear wheel. In a particular embodiment the wheelchair has the special feature that the two first middle sub-frames are mutually connected by a first spacer. In another embodiment the wheelchair has the special feature that the block is hingedly connected to the second middle sub-frame and the two second middle sub-frames are mutually connected by a second spacer. In particular a combination of the two latter special features provides a strong and stable mechanical structure, wherein the whole space under the said two spacers is freely accessible. This may be of importance for coupling of the wheelchair to an auxiliary device such as described in applicant's earlier, as yet unpublished Netherlands patent application NL-93 01322 which is based on the European priority patent application EP-93.201601.1 of 4 June 1993. A still greater stiffness is ensured with a variant wherein the two rear sub-frames are mutually connected by a third spacer in the zone adjoining the first middle sub- frame. A very simple, reliable embodiment of the wheelchair according to the invention has the characteristic that the stop means comprise a pin axially displaceable by means of actuating means counter to the action of spring means, which pin is mounted in a sub-frame and can be in locking co-action with a hole in an adjacent sub-frame. The construction of the wheelchair is preferably symmetrical. In this respect the said embodiment can have the special feature that two pins are present at corresponding positions in both its frames. Easy to operate is the embodiment in which the two pins are connected by a flexible pulling member, for example a cord or cable, such that by exerting a pulling force on that pulling member a user can move both pins out of their locking co-action with the respective hole counter to the action of the respective spring means. The invention will now be elucidated with reference to the annexed drawings. Herein: figure 1 shows a partly broken away perspective view of a wheelchair according to the invention; figure 2 shows a partly broken away perspective view on enlarged scale of the structure in the region of the coupling block for the left-hand rear wheel; figure 3 is a schematic side view of the wheelchair in which the manner of folding is indicated; figure 4 is a perspective view of the wheelchair in folded state after the rear wheels have been removed; figure 5 is a side view of a variant; figure 6 is a side view of the wheelchair of figure 5 which is coupled to an auxiliary device as according to NL-93 01322; and figure 7 shows a partly broken away perspective view of a detail of a variant. In all figures the same components are designated with the same reference numerals. Figure 1 shows a collapsable wheelchair according to the invention. The wheelchair comprises a left-hand side frame 2 and a right-hand side frame 2' . These side frames 2 and 2' are the same but embodied mirror symmetrically. For the sake of brevity in the description only side frame 2 will be described where appropriate. Side frame 2 comprises: a first middle sub-frame 4 which in the operative state shown in figure 1 extends more or less horizontally, in any case roughly at the height of a seat 5; a front sub-frame 6 which in the operative situation shown in figure 1 extends from the front side of the first middle sub-frame 4 inclining downward in forward direction and which bears a support member 7 for a foot-rest and a relatively small pivotable front wheel 8; a rear sub-frame 9 which in the operative situation shown in figure 1 extends from the rear side of the first middle sub-frame 4 inclining upward in rearward direction and which bears a relatively large rear wheel 29 and together with the other rear sub-frame 9' supports a seat back 10. The front sub-frame 6 and the rear sub-frame 9 are pivotable relative to the first middle sub-frame 4 by means of respective hinge joints 11, 12. The support member 7 mutually joins the left and right-hand front sub-frames and thus contributes to the self-supporting character of the wheelchair. The side frames 2, 2' are connected to coupling means. These are embodied as spacers holding corresponding sub- frames at fixed mutual distance. The first middle sub-frames 4, 4' are coupled by means of a spacer 13. The rear sub- frames 9, 9' are coupled by a spacer 14. A second middle sub- frame 17 is arranged between the front sub-frame 6 and the rear sub-frame 9 for pivoting relative to both these sub- frames by means of hinge joints 15, 16 such that each side frame 2, 2', and thus the whole frame, can be folded round horizontal pivot axes until the three sub-frames 6, 4, 9; 6', 4', 9' lie at least substantially on top of each other. Present between the first middle sub-frame 4 and the front sub-frame 6 are stop means which determine a stable operating position of wheelchair 1. Connected to the front sub-frame 6 for this purpose is a pin 18 which is movable in a slotted hole 19 in the first middle sub-frame 4 which is concentric to joint 11. The location of the hinge joint 12 between the first middle sub-frame 4 and 9 is adjustable along that rear sub- frame 9. Particular reference is made in this respect to figure 2. A sleeve 20 is slidable along the rear sub-frame 9 and fixable relative thereto in chosen positions by means of holes 21 and a pin 22. Sleeve 20 carries two ears 23 which hingedly support the first middle sub-frame 4 by means of a bolt 24. The corresponding sleeves 20, 20' are mutually connected by a tube 25 which serves as spacer, therefore stiffens the construction and also fulfills the function of support for the seat 5 which is supported at the front by the spacer 13. The location of the hinge joint 15 between the second middle sub-frame 17 and the front sub-frame 6 is adjustable along that front sub-frame. For this purpose a series of holes 39 is arranged in that sub-frame 6. The length of the second middle sub-frame 17 is adjustable. The embodiment of this adjustability is of a per se known type, related to the adjustment of the sleeve 20 relative to the rear sub-frame 9 as shown in figure 2. This does not therefore require further discussion. In wholly analogous manner the support member 7 is adjustable relative to the front sub-frame 6. The first middle sub-frame 4 has in the main plane of the side frame a larger dimension than in transverse direction for increasing the bending stiffness in that plane. Figure 1 shows that the relevant dimension increases as the distance to the hinge joint 11 decreases. The front sub-frame 6 has in the main plane of the side frame a larger dimension than in transverse direction for increasing the bending stiffness in that plane. As this front sub-frame 6 is subject to a less strong moment than the first middle sub-frame 4 the relevant dimension does not have to be as large as in the case of the first middle sub-frame 4. The rear wheel 29 is coupled to the rear sub-frame 9 by means of a per se known rapid-action coupling 40. Particular reference is made in this respect to figure 2. The rear sub- frame 9 bears for this purpose a block 26 which is releasably coupled thereto by means of a bolt 25 and which supports a shaft 27 to which the rear wheel 29 is detachably coupled by means of rapid-action coupling 40. The block 26 carries the shaft 27 at an angle determining the alignment angle of rear wheel 29. Block 26 carries the spacer 14 pivotally. The second middle sub-frame 17 is connected to spacer 14 by means of a weld joint 28. The position of shaft 27 is adjustable at least roughly in the travel direction of the rear wheel 29. To this end the block 26 is provided with a slotted hole 30 in which shaft 27 is slidable. Fixation in a desired position takes place by means of a nut 31. The block 26 is easily detachable so that if desired it can be replaced with another block with which a user can obtain another desired alignment angle of rear wheel 29. Figure 3 shows a side view of wheelchair 1 elucidating the manner in which folding takes place. It will be apparent that the respective sub-frames 9, 4, 6, 17 can be folded while pivoting mutually until they assume a mutual position occupying the minimum space. Figure 4 shows in perspective view this folded situation. Figure 5 shows a side view of a wheelchair 32 which differs from wheelchair 1 according to figures 1-4 insofar that the first middle sub-frame 33, at variance with sub- frame 4 of figures 1-4, has an open structure. With the perforations, all designated with 34 for the sake of convenience, the bending stiffness is reduced to only a negligible extent, although a considerable weight reduction is realized. Attention is drawn to the fact that in the situation shown in figure 5 and the figure 6 to be discussed here- inbelow the blocks 26, 26' have a reversed position. The user hereby acquires a still greater adjustability of the position of rear wheels 29, 29' . Figure 6 shows the coupling of wheelchair 32 to an auxiliary device as according to applicant's earlier, as yet unpublished Netherlands patent application NL-93 01322 which is based on the European priority patent application EP-93.201601.1 of 4 June 1993. This auxiliary device 35 can be coupled in very simple manner to wheelchair 32 and then provides the user with a manual control 36 for driving and steering wheelchair 32 by means of the front wheel 37 forming part of auxiliary device 35. The front wheels 8, 8' of wheelchair 32 are raised from the ground in the coupled situation of wheelchair 32 and auxiliary device 35. The combination 32, 35 therefore travels only on rear wheels 29, 29' and front wheel 37. Essential to the coupling between auxiliary device 35 and wheelchair 32 is the structure according to the invention, according to which the spacers 13, 14 are freely accessible from the front without this accessibility being obstructed by the presence of a pivotable cross frame as according to the prior art. The rear sub-frames 9, 9' are coupled at their top, in the region of the seat back 10, by a hand-grip 38 which can serve for manual propulsion of wheelchair 1, 32 by a third party. Attention is drawn to the fact that block 26 is embodied such that it essentially forms an integrating component of the frame. Figure 2 in particular shows this aspect clearly. Block 26 is embodied such that it can support the tubular sub-frame 9 with bending stiffness. For this purpose block 26 must be manufactured from a material which can resist the associated mechanical load. Such a material is for instance aluminium. Attention is drawn to the fact that the second middle sub-frame 17 has an adjustable length. In combination with the series of fastening holes 39 corresponding with the positions at which the second middle sub-frame 17 is connected to the front sub-frame 9, this ensures the desired adjustability with the correct collapsability, i.e. a collapsability into the position shown in figure 4 in which the respective sub-frames lie on top of one another taking up the minimum of space. The frame of the wheelchair according to the invention is wholly self-supporting and has considerable bending stiffness. A width adjustment is very simple to realize, if desired. The diverse cross connections shown in figure 1 between both side frames can be replaced for this purpose with elements with adapted length. These adaptations are wholly linear and correspond exactly with the desired width adjustment. In known collapsable wheelchairs with for instance scissor mechanisms such adaptations are not linear with the desired width adjustment. Diverse materials are suitable for the frame. These are for instance metals, in particular light materials such as aluminium, plastics, optionally with fibre rein orcement, of great mechanical strength, for instance ABS, in addition to sandwich and composite structures. It will be further apparent that the spacer 13 can also be arranged at other positions in the vicinity of the hinge joints 11, subject to design considerations. With reference to the embodiment of figure 5 and figure 6 it is finally noted that the continuous holes or perforations 34 in the middle sub-frame 33 have dimensions which decrease in transverse direction relative to the longitudinal direction of that sub-frame 33, running from the hinge joint 11 to the hinge joint 12. Figure 7 shows that an axially displaceable locking pin 51 is mounted on both sides in the first sub-frame 6. This comprises a collar 52 which serves as stop for a pressure spring 53 which serves to carry the pin 51 outward into a blind hole 54 which is present in the middle sub-frame 4' and with which the pin 51 can thus co-act for locking. As a result of the distance between the hinge joint 11' and the pin-hole connection 51,54 the sub-frames 4 ',6 are mutually connected so as to be locked against rotation. A cord 55 mutually connects the pins 51 in the left and right-hand frame. By exerting a pulling force on cord 55 a user can pull the pins 51 inward counter to the action of the respective springs 53, whereby the hinge locking between sub-frames 4',6 is disengaged and the wheelchair can be collapsed.

Claims: Claims 1. Collapsable wheelchair comprising: a frame comprising: a fir.7t side frame; a second side frame substantially the same as the first side frame; coupling means holding the two said side frames at least in the operative situation in the same positions at a mutual distance; wheels arranged on the frame; a seat arranged on the frame,- and a seat back arranged on the frame; characterized in that each side frame comprises: a first middle sub-frame which in the operative situation extends more or less horizontally, at least roughly at the height of the seat; a front sub-frame which in the operative situation extends from the front side of the first middle sub-frame inclining downward in forward direction and which bears a relatively small front wheel; a rear sub-frame which in the operative situation extends from the rear side of the first middle sub-frame inclining upward in rearward direction and which bears a relatively large rear wheel and together with the other rear sub-frame supports the seat back; the front and rear sub-frames are pivotable relative to the first middle sub-frame by means of a hinge joint; the coupling means are embodied as spacers holding corresponding sub-frames at fixed mutual distance; a second middle sub-frame is arranged between the front and rear sub-frame for pivoting relative to both these sub- frames by means of a hinge joint such that each side frame, and thus the whole frame, can be folded round horizontal pivot axes until the three sub-frames lie at least substantially on top of each other; and stop means are present between a middle sub-frame and at least one of the other sub-frames which determine a stable operating position of the wheelchair. 2. Wheelchair as claimed in claim 1, characterized in that the location of the hinge joint between the first middle sub-frame and the rear sub-frame is adjustable along that rear sub-frame. 3. Wheelchair as claimed in claim 1, characterized in that the location of the hinge joint between the second middle sub-frame and the front sub-frame is adjustable along that front sub-frame. 4. Wheelchair as claimed in claim 1, characterized in that the length of the second middle sub-frame is adjustable. 5. Wheelchair as claimed in claim 1, characterized in that in the main plane of the side frame and at least in the zone adjoining the hinge joint to the front sub-frame the first middle sub-frame has a larger dimension than in transverse direction for increasing the bending stiffness in that plane. 6. Wheelchair as claimed in claim 5, characterized in that in the main plane of the side frame and at least in the zone adjoining the hinge joint to the first middle sub-frame the front sub-frame has a larger dimension than in transverse direction for increasing the bending stiffness in that plane. 7. Wheelchair as claimed in claim 1, characterized in that the rear wheels are releasably coupled to the rear sub- frame by means of a rapid-action coupling. 8. Wheelchair as claimed in claim 7, characterized in that the rear sub-frame bears a releasable block which supports a shaft to which a rear wheel is releasably coupled, which block supports the shaft at an angle determining the alignment angle of the rear wheel. 9. Wheelchair as claimed in claim 8, characterized in that the position of the shaft is adjustable in the travel direction of the rear wheel . 10. Wheelchair as claimed in claim 1, characterized in that the two first middle sub-frames are mutually connected by a first spacer. 11. Wheelchair as claimed in claim 8, characterized in that the block is hingedly connected to the second middle sub-frame and the two second middle sub-frames are mutually connected by a second spacer. 12. Wheelchair as claimed in claim 1, characterized in that the two rear sub-frames are mutually connected by a third spacer in the zone adjoining the first middle sub- frame. 13. Wheelchair as claimed in claim 1, characterized in that the stop means comprise a pin axially displaceable by means of actuating means counter to the action of spring means, which pin is mounted in a sub-frame and can be in locking co-action with a hole in an adjacent sub-frame. 14. Wheelchair as claimed in claim 13, characterized in that two pins are present at corresponding positions in both its frames. 15. Wheelchair as claimed in claim 14, characterized in that the two pins are connected by a flexible pulling member, for example a cord or cable, such that by exerting a pulling force on that pulling member a user can move both pins out of their locking co-action with the respective hole counter to the action of the respective spring means.

Inventors: BRAAM HARM HENDRIK, ORDELMAN HENDRIK JAN, STOKKERS HERMAN WILLEM HENDRIK, TEMMINK GERHARD, BRAAM, HARM, HENDRIK, ORDELMAN, HENDRIK, JAN, STOKKERS, HERMAN, WILLEM, HENDRIK, TEMMINK, GERHARD
Applicants: BRAAM HARM HENDRIK, ORDELMAN HENDRIK JAN, STOKKERS HERMAN WILLEM HENDRIK, TEMMINK GERHARD, BRAAM, HARM, HENDRIK, ORDELMAN, HENDRIK, JAN, STOKKERS, HERMAN, WILLEM, HENDRIK, TEMMINK, GERHARD
Application year: 1994
Main classification: A61G5
IPC codes: A61G5